Some aircraft brake assemblies include one or more brake rotors that rotate with an aircraft wheel and one or more brake stators that extend between the rotors and are fixed with respect to aircraft landing gear. The rotors and stators are arranged in an alternating manner to form a brake disk stack and are normally spaced so that the aircraft wheel can rotate freely. To apply braking force, the disk stack is compressed by an actuator and surfaces of the rotors and stators are forced into contact to slow and/or stop rotation of the aircraft wheel.
Various types of actuators may be used to apply pressure against the disk stack to compress the disk stack, including hydraulic actuators and electric actuators. In electric brake actuators, an electric motor receives electrical power from an aircraft power system and is controlled by electrical signals from an aircraft control system. The electric motor may be coupled to a motor shaft, which rotates under power of the electric motor. The motor shaft is coupled to a ram or piston that converts rotational motion of the motor shaft to linear motion of the ram or piston. The motor moves the ram or piston toward and away from the disk stack to apply and release pressure on the disk stack, respectively. The assembly of motor, shaft, and ram or piston may be referred to as an electromechanical actuator (EMA).